a ball and chain

This expression arose from the former bakers' practice of adding an extra loaf to a dozen sold to a retailer - this representing the retailer's profit.

turn the balance = turn the scales

alter the probability of the outcome

weigh something in the balance

carefully ponder or assess the merits and demerits of something.

The image is of a pair of old-fashioned scales with two pans in which the positive and negative aspects of something can be set against each other. The expanded phrase weighed in the balance and found wanting meaning having failed to meet the test of a particular situation'is also found, and is an allusion to the biblical book of Daniel, where such a process formed part of the judgement made on King Belshazzar.

as bald as a coot

completely bald

The coot {Fulica atra) has a broad white shield extending up from the base of its bill. The history of the word bald is somewhat obscure, but analogies with other northern European languages suggest a connection with the idea of having a white patch or streak.

a ball and chain

a severe hindrance

Originally, a ball and chain referred to a heavy metal ball attached by a chain to the leg of a prisoner or convict to prevent their escape.

the ball is in someone's court

It is that particular person's turn to act next.

This expression is a metaphor from tennis or a similar ball game where different players use particular areas of a marked court.

a ball of fire

a person who is full of energy and enthusiasm

In the early 19th century this phrase was also used to mean a glass of brandy.

behind the eight ball

at a disadvantage

baffled - North American

The black ball is numbered eight in a variety of the game of pool known as eight-ball pool.

have a ball

enjoy yourself greatly

have fun – informal

have the ball at your feet

have your best opportunity of succeeding.

have a lot on the ball

have a lot of ability – US

keep the ball rolling

maintain the momentum of an activity.

keep your eye on the ball

keep your attention focused on the matter in hand.

take your eye off the ball

fail to keep your attention focused on the matter in hand.

on the ball

alert to new ideas, methods, and trends – informal

1998 - Romesh Gunesekera - Sandglass - It's big business now, you know. You have to be on the ball…go, go, go all the time.